Scientists discover two new 'super-Earth' planets that may support life

The two worlds at the edges of star Tau Ceti's "habitable zone" are part of a system of planets that are similar in size to our own.

Within this zone the temperature is not too hot or not too cold, just comfortable for the existence of surface waters.

Researchers led by Fabo Feng from the University of Hertfordshire in the United Kingdom detected the four exoplanets by registering extremely slight wobbles in Tau Ceti's movement, due to the gravitational pull of smaller astronomical bodies.

Spectroscopy is a technique that, according to NASA's website "measures light that is emitted, absorbed, or scattered by materials".

To see whether the planets have the right environmental conditions to support life, the researchers have to improve the sensitivity of the radial velocity technique to 10 centimetres (4 inches) per second.

Each of these two planets has masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby Sun-like stars, they said.

The Herefordshire-Santa Cruz team previously collaborated on a study of Tau Ceti in 2013, a study that concluded that five much larger "super-Earth" planets orbited the star.

"But no matter how we look at the star, there seems to be at least four rocky planets orbiting it", Dr Tuomi said.

An global team of astronomers, led by the University of Hertfordshire, has discovered two potentially habitable planets. Tau Ceti, a favorite destination of writers of science fiction, very similar to the Sun in size and brightness.

The astronomers analyzed data on the wavelength of star light received from the European southern Observatory in Chile and the Keck Observatory on Mauna Kea, Hawaii. Unlike more common smaller stars, such as the red dwarf stars Proxima Centauri and Trappist-1, they are not so faint that planets would be tidally locked, showing the same side to the star at all times.

As far as habitability goes, the researchers themselves point out another problem: due to the massive debris disk surrounding tau Ceti, the outer two planets are likely subject to intense bombardment via comets and asteroids, which would pose obvious issues for life.